Unlocking SIM Cards With A Logic Analyzer

January 2, 2020 by 20 Comments

[Jason Gin] wanted to reuse the SIM card that came with a ZTE WF721 wireless terminal he got from AT&T, but as he expected, it was locked to the device. Unfortunately, the terminal has no function to change the PIN and none of the defaults he tried seemed to work. The only thing left to do was crack it open and sniff the PIN with a logic analyzer.

This project is a fantastic example of the kind of reverse engineering you can pull off with even a cheap logic analyzer and a keen eye, but also perfectly illustrates the fact that having physical access to a device largely negates any security measures the manufacturer tries to implement. [Jason] already knew what the SIM unlock command would look like; he just needed to capture the exchange between the WF721 and SIM card, find the correct byte sequence, and look at the bytes directly after it.

Finding the test pads on the rear of the SIM slot, he wired his DSLogic Plus logic analyzer up to the VCC, CLK, RST, and I/O pins, then found a convenient place to attach his ground wire. After a bit of fiddling, he determined the SIM card was being run at 4 MHz, so he needed to configure a baud rate of 250 kbit/s to read the UART messages passing between the devices.

Once he found the bytes that signified successful unlocking, he was able to work his way backwards and determine the unlock command and its PIN code. It turns out the PIN was even being sent over the wire in plain text, though with the way security is often handled these days, we can’t say it surprises us. All [Jason] had to do then was put the SIM in his phone and punch in the sniffed PIN when prompted.

Could [Jason] have just run out to the store and picked up a prepaid SIM instead of cracking open this wireless terminal and sniffing its communications with a logic analyzer? Of course. But where’s the fun in that?

Building A Giant Meta-Clock Made Of Smaller Clocks

January 1, 2020 by 18 Comments

Have any last-minute projects you finished just before the end of the decade? To help pass the time, [Erich Styger] decided to build a meta digital clock made up of 24 individual analog clocks, the perfect item to help welcome in the new year. The stepper clock is controlled by a network of LPC microcontrollers, displaying the time and room temperature, as well as several aesthetically pleasing loading animations.

Each clock operates from a 5 V USB power bank drawing less than 2 A for the full 24-clock setup. The meta-clock resides in a laser cut enclosure, with 3D printed hands telling the time. While having one board per clock would be easier to implement, [Erich] decided to use one board per four clocks arranged in rows to save on costs. The arrangement fixes the distance between clocks, though [Erich] also made the clock size slightly smaller to compensate.

The ‘stepper’ part of the stepper clock uses a 360 degree version of the VID28 stepper motor to reduce the height of the design and the cost of the project. Apart from the X12.017 driver silently driving the motors, the stepper motors also conveniently only need a ‘direction’ and ‘step’ pin, reducing the pin count needed for the microcontroller. Neodymium magnets and hall effect sensors are used for tracking the position of the hands as the clocks move, with the magnets embedded into the clock hands.

As for communication, rather than use the common I2C protocol, the more robust RS-485 was selected. A master coordinates all of the clocks using the bus, providing a command line interface. The master is also able to communicate with the host PC over USB to maintain RTC time.

During the software development phase, [Erich] made use of the SEGGER J-Link EDU mini CLI for keeping track of information about the driver and each individual stepper motor. The software controlling the motors is written in C, with boards running FreeRTOS. The stepping is handled with a timer interrupt, but because the LPC845 doesn’t have enough timer channels, all of the functionality is done within a single channel. This results in plenty of interrupt handlers, flags, and callbacks across the code, which makes for some good fun.

Speaking of clocks, check out some of our other past clock hacks, including this mini-VFD clock and this fun LED matrix clock (it lets you play Tetris!)

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Analog Meter Clock Uses Parts From A Simpler Time

December 29, 2019 by 16 Comments

Clocks with hands that turn are all well and good for the common folk, but hacker types prefer something different. [Sjm4306] is one such person, and developed this analog dial clock with parts we’d almost consider retro by modern standards.

The microcontroller at the heart of the build is a PIC16F886. An 8-bit micro from the Microchip brand, it features no Arduino bootloader or USB interface, being flashed via a dedicated programmer. This is combined with a DS1302 real-time clock to keep accurate time, and a MCP4922 DAC which is responsible for generating the output to drive the dials. The dials themselves are sourced from eBay, being simple voltmeters. They’re given a new backing to display hours and minutes instead of volts, and backlit with LEDs for style.

In this day and age, we’re more used to seeing high-end micros used with integrated DACs and USB programming, but it’s nice to see the parts of yesteryear being used, too. It’s not the first clock we’ve seen from [sjm4306], either. Video after the break.

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Word Clock Does The Job With Laser-Etched Acrylic

December 26, 2019 by 6 Comments

As far as telling the time, word clocks go out of their way to spell it out for you. As long as you know the language, they’re a stylish and effective way to get the message across. [Simon] built an elegant, stripped-back word clock of his own, with a laser cutter helping to get the job done.

The core of the build is an Arduino Nano, hooked up to a string of 22 WS2812B LEDs, driven via the FastLED library. An NXP PCF8563T serves as the real-time clock, to ensure stable and accurate timekeeping. The electronics are all housed inside an enclosure that appears to be constructed from PCBs, with instructions on operating the clock printed on the base.

The actual display is via laser-cut and laser-etched acrylic. The display piece slides into the top of the clock, with the LEDs edge lighting various segments to display the relevant words that make up the current time. The clock is designed in such a way that these display slides can be easily switched out to change the look of the clock, with different fonts and designs.

It’s a quick and clean take on the popular word clock design, and one any makerspace could whip up in a weekend. As far as word clocks go, however, the sky really is the limit when it comes to complexity. Video after the break.

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Color Coded Clock Runs On Roman Numerals

December 24, 2019 by 2 Comments

Roman numerals are, by modern standards, a bit unusual. By virtue of using designations for both 5 and 10, and not scaling well to higher numbers, they’ve fallen out of favor outside of some specific uses. One of those is in time keeping, in which many clocks use the classical numerals instead of the more popular Arabic replacements. [Nicola]’s clock does too, albeit in a rather unusual way.

A diagram of the clock displaying the times 18:40 and 23:04.

The build begins with a faux-neon palm tree LED decoration, which is gutted and refitted with a WS2812B LED strip, run by an Arduino Nano. An RTC is used to keep accurate time, and the time is set by running a one-off program to initialise the clock.

To tell the time, the LEDs are color coded. However, instead of using a binary representation that many can find unfamiliar, colors are chosen instead to correspond to Roman numerals. Blue, green, red and yellow are chosen to represent 1, 5, 10, and 50, or I, V, X, and L respectively. The Github has more details for the curious. The clock uses 24 hour time, and we think we’ve figured out how the display works – with hours on the left and minutes on the right.

It’s fun to see an LED clock that takes a different bent on the usual themes. We’ve seen plenty over the years, from the byte clock to this stunning blinkenlights build. If you’ve cooked up your own special timepiece, be sure to let us know.

Tiny Bubbles In The Clock

December 20, 2019 by 9 Comments

When [DonHo] sang about tiny bubbles, he probably wasn’t thinking of them embedded in glycerine. But that’s where the bubbles in [ShinodaY]’s clock reside. The viscous fluid holds the bubbles better allowing the time to be read more easily. You can watch the relaxing display in the video below.

The theory of operation is simple and reminds us somehow of a reverse Tetris game. Solenoid valves at the base release air bubbles to form a row of the display. The bubbles rising makes room for the next row. The display has as many columns as there are air outlets at the bottom. Spacing the bubble pixels is as simple as adjusting the timing between air bubbles.

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Numitron Clock Is A Tidy ’70s Throwback

December 20, 2019 by 13 Comments

As far as hacker clock builds go, the more obscure the parts involved, the better. By this yardstick, [sjm4306] has a great piece on his hands with this Numitron-based build.

The Numitron was a type of display popular in the 1970s, and often used in aircraft avionics and other high-end hardware. The display is a 7-segment type, but using filaments instead of LEDs. [sjm4306] was able to lay his hands on four of these devices, along with some bulbs to act as the digit seperator and AM/PM indicator. Due to being incandescent in nature, multiplexing wasn’t a practical option, with lower duty cycles drastically dimming the display. Instead, a 32-bit cascaded shift register was used to enable all the segments to be driven at the same time.

It’s a great build that uses some genuine original display hardware to create a clock with a compelling vintage aesthetic. This would make a great gift to a pilot from the era, or any hacker that likes the unusual display technologies of yesteryear. You can even build a Numitron watch, if you’re so inclined. Video after the break.

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